Plug Welds

[Artisan]

Can I ask the pros what a proper size is for a plug weld?

.375?
.500?

This is a .250 thick plate about 4"x3" and I drew in 4- .500" holes.
I will be marrying this to a similar solid plate below.

 

[Shield Arc]

Can I ask the pros what a proper size is for a plug weld?

.375?
.500?

This is a .250 thick plate about 4"x3" and I drew in 4- .500" holes.
I will be marrying this to a similar solid plate below.

I'm not a pro, so please forgive me for jumping in.

I can't tell you how many plug welds I've made in my life, but I don't think there are any rules. But I thought it was a very good question so I looked in the Lincoln Procedure Handbook. Which states:
The principal consideration in making plug welds is to be sure that the weld fuses to both plates and completely fills the hole. A weld of 3/4-in. Diameter is normally the maximum size used for plug welding. Larger plugs are sometimes made with semiautomatic equipment by circulating the arc around the plug to completely fill the hole. Plugs up to 2-in. In diameter and 2-in. Deep are made in this manner.

AWS D1.1 book says:
The depth of filling of plug or slot welds in metal 5/8-in. Thick or less shall be equal to the thickness of the material. In metal over 5/8-in. Thick, it shall be at least one-half the thickness of the material but no less than 5/8-in.

 

[Artisan]

Thank YOU!